Snap action electric switch



Oct. 6, 1970 y H. JAKoBs 3,533,040

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arvnfwwjmhyy@ United States Patent 3,533,040 SNAP ACTION ELECTRIC SWITCH Hans Jakobs, Schaumburg Township, County of Cook, Ill., assignor to C. E. Nicholl & C0., Chicago, Ill., a corporation of Illinois Continuation-in-part of application Ser. No. 597,045, Nov. 25, 1966. This application Mar. 11, 1968, Ser. No. 712,038

The portion of the term of the patent subsequent to Feb. 24, 1987, has been disclaimed Int. Cl. H01h 61 06 U.S. Cl. 337-136 6 Claims ABSTRACT OF THE DISCLOSURE A snap action electric switch co-mprising a flexible snapL acting metallic vane with vane biasing means and longitudinally expansible contact carrying pull wire means overlying the opposite surfaces of the vane and tensioned to flex the vane in opposite directions between two positions in response to alternate heating and cooling of the pull wire.

Cross-references to related applications This application is a continuation-in-part of applicants copending application Ser. No. 597,045, led Nov. 25, 1966, and assigned to the assignee of this application. This application also discloses features disclosed and claimed in applicants contemporaneously led application Ser. No. 711,953, tiled Mar. 11, 1968, now Pat. No. 3,518,598, assigned to the assignee of this application.

Field of the invention The invention pertains to snap action electric switches operated by the alternate heating and cooling and the resultant expansion and contraction of an element generally called pull means or a pull wire. Most often the switches are used to control the flashing of automotive signal lights, such as turn signals.

Description of the prior art Snap action switches of the character set forth immediately above are well kno-wn and of various constructions. Many include a exible vane that is creased and thus biased into one position by inherent or intrinsic stresses in the vane. The devices disclosed and claimed in the above referred to copending applications utilize substantially flat unstressed exible vane with separate biasing means and pull wire so arranged that alternate heating and cooling of the pull wire results in snap action movement of the vane and an associated contact on the vane or pull Wire between two positions.

Summary of the invention A reliably operating snap switch that can be constructed simply and economically is provided by construction of a snap switch with a generally octagonal vane having a narrow slot pojecting inwardly from one corner or end toward the center of the vane and supported at a point between the inner end of the slot and the opposite end of the vane and somewhat off the line of the slot. Vane biasing means in the form of a tensioning strap is attached to opposite sides of the vane to overlie one side of the vane substantially transversely of and somewhat off the center of the length of the slot. A directly heated pull wire overlying the opposite side of the vane is secured substantially centrally of the vane and substantially parallel to the biasing strap near the inner or closed end of the slot. The pull wire carries a contact substantially centrally of its length and the pull wire and tensioning strap are so adjusted that the vane moves with snap action be- 3,533,040 Patented Oct. 6, 1970 ICC Brief description of the drawing Other objects and advantages of the present invention will become apparent from the ensuing description of an illustrative embodiment thereof, in the course of which reference is had to the accompanying drawing, in which:

FIG. 1 is a side view of the snap action switch of the present invention, viewed from the pull wire side;

FIG. 2 is a side view of the switch from the opposite or tensioning strap side;

FIGS. 3 and 4 are sectioned views taken along the lines 3-3 and 4-4 of FIG. 1 illustrating a first position of the vane with respect to the biasing and pull wire means, respectively, when the pull wire means is in its cold unexpanded or contracted position; and

FIGS. 3A and 4A are views corresponding to FIGS. 3 and 4, but illustrating a second position of the vane with respect to the biasing and pull wire means, respectively, when the pull wire means is in its heated expanded condition.

FIGS. 3 and 4 are dimensionally enlarged in order better to illustrate the construction and operation of the vane with relation to its associated biasing and pull wire means.

Description of the preferred embodiment Referring now to the drawing, the snap action switch device of the present invention is generally designated by the reference character 10. It includes, in the main, a flexible resilient metallic vane 12 of generally octagonal shape, biasing means 14 comprising a strap overlying one surface of and attached to opposite edges of the vane adjacent one end, and pull wire means comprising a longitudinally expansible pull wire 16 of the directly heated type and attached to opposite edges of the vane and positioned substantially centrally of the vane parallel to the strap 14. The vane 12 is substantially flat and inherently unstressed. It is provided with a narrow slot 12A extending from the aforesaid one corner or end to near the center of the vane. It is also provided with a short rib 0r projection 12B spaced from and parallel to the slot and projecting toward the strap 14 to provide a limit angular relationship between the pull wire and strap in the condition illustrated in FIG. 3 so that the strap will more effectively and reliably return the vane to the position illustrated in FIG. 3A.

As will be described in greater detail hereinafter, the biasing strap is tensioned and exes the vane in one direction to position the vane away from the strap, as best illustrated in FIG. 3A. The length of the pull `wire is such that in its cold unexpanded or contracted position it is tensioned and exes the vane in the opposite direction, i.e., toward the strap, see FIGS. 3 and 4. The biasing strap and pull wire are effective in response to alternate heating and cooling and resultant expansion and contraction of the pull wire to move the vane by snap action between its two positions, Movement of the vane is utilized to move a contact 16A mounted on the pull wire relative to a stationary contact or contacts, such as contact 18 associated therewith, thereby to provide desired circuit controlling functions.

As disclosed in the contemporaneously led applicathe vane 12 by the ribs, which are located near opposite edges of the vane. The ribs are disposed transversely of the pull wire, and project away from the plane of the vane at the pull wire side. The ends of the vane beyond the ribs have small triangular corner portions 12C that are bent slightly in a direction opposite to the projection of the ribs and to which the opposite ends 16B of the pull wire are secured. The ribs project but slightly but enough to prevent any substantial contact and undesired bending of the pull wire by the vane. The rib A is shown extending only part way across the vane. Actually the ribs are required only under the pull wire.

As is the case with the 'vanes of my copending applications, the 'Vane can be formed by a stamping operation or operations in which the Ivane is initially cut into the slotted octagonal configuration and with the ribs and outer triangular portions 12C formed thereon. The ribs, however, do not disturb the substantially fiat construction of the vane nor do they provide any inherent or intrinsic stresses in the vane which need to be relieved by heat treatment or othenwise.

The biasing strap 14 is attached to flats 12D at alternate points of the vane and extends transversely of the slot and overlies the surface of the vane at the side opposite the pull wire. The strap comprises a strip of metal having a length somewhat longer than the distance between points 12D. The ends 14A of the biasing strap are spot welded in place. The effective length of the biasing strap |14 is such as to flex the vane away from the biasing strap and transversely of the direction of the bias, to a position substantially as illustrated in FIG. 3A. Thus, when the pull Wire is hot and in its expanded condition the biasing strap effects snap movement of the vane to the position of FIG. 3A. Adjustment of the magnitude of the bias can be conveniently and easily adjusted by bending at tlat regions 12D of the vane and such adjustment of the strap may be effected independently of the pull wire.

The rib 12B, as indicated earlier, limits the relative movement of the vane and strap toward each other in the cold condition of the pull wire, as illustrated in FIG. 3. This limitation of movement results in a small angle between the halves of the strap at the sides of the rib and vane to space them, better to insure return operation of the vane to the position of FIG. 3A by the biasing means when the pull wire is heated and expanded. In the position of =FIG. 3A, the strap and rib are spaced 4apart a slight distance.

The pull wire 16 overlies another surface of the vane and is attached to and extends centrally of the vane between the opposed triangular portions 12C. The pull wire comprises a strip of electrically conductive material, preferably metallic and heat expansible in a longitudinal direction, having a length slightly in excess between the portions 12D. The pull wire is attached at its ends 16B to the vane by means of crimping and welding and the ribs 20 space the pull wire slightly from the adjacent surface of the vane 12. In the heated condition of the pull wire, see FIG. 4A, the latter approaches the surface of the vane somewhat but has no substantial engagement with it, so that, as earlier noted, there is no substantial engagement or undesired bending of the pull wire by the vane.

The vane 12 moves with snap action between two positions. In what may be termed a first position in which the pull wire 16 is cold but ready to be heated the contact 16A mounted at the center of the pull wire is engaged with the associated fixed contact 18 mounted upon a conductive bracket 22 of suitable shape. The opposite half of the vane is ixedly secured to a bracket type support 24, the mounting being effected by a spot weld 26 in line or slightly off line with respect to slot 12A, to an intermediate portion 24A of the bracket. The bracket is provided with a somewhat transversely extending end portion 24B which extends toward the vane and against which the vane may abut in the aforesaid second position.

Referring particularly to FIGS. 1 and 2, it may be noted that the device 10 includes a base 30 preferably formed on non-conductive material, such as molded plastic. The device generally includes a cover (not shown) engageable with the base and associated element. Extending downwardly from the base are a plurality of plug-in type terminal members, of which two, indicated by the reference characters 32 and 34, are illustrated. These terminals are connected to the supports 22 and 24, respectively, by conductive rivets 36. In use, the terminals are connected to a suitable source of power and generally in series with a lamp or lamps which are to be flashed by the snap switch.

Alternate heating and cooling of the pull wire 16 to effect alternate expansion and contraction of the pull wire may be accomplished in any desired manner. In the illustrated device the pull wire 16 is heated directly by current ow through it by reason of the engagement of contacts 16A and 18. The circuit arrangement is such that the pull wire is energized in the indicated position of the vane, assuming that a source of electricity is connected to the terminals. When the pull wire expands and the vane moves to its other position to effect disengagement of contacts 16A and 18, the heating element is deenergized and cools. Signal lights may be in circuit with one of the terminals so that when the contacts are engaged the lights are energized and lighted; when the contacts are disengaged the lamps are not lighted.

In operation, the vane 12 is normally in the position illustrated in FIGS. `1 through 4, wherein the pull wire 16 is in its cold, contracted or unexpanded condition. In this position the vane is flexed by the pull wire in the direction toward the biasing strap 14 to a position in which pull wire contact 16A engages contact 18. Also, the rib 12B on the vane engages the biasing strap 14. At this time the associated signal lights are energized and lit.

After the pull wire 16 is heated for a period of time, it expands to an extent enabling the biasing strap 14 to snap vane 12 to its alternate position, as illustrated in FIGS. 3A and 4A. The vane moves abruptly with snap action to effect movement of the pull wire and disengagement of contacts 16A and 18, and movement of the vane and biasing strap to the position of FIG. 3A. In this position the rib 12B is slightly spaced from the strap 14. The alternate snapping of the vane is an over-center movement in line with the slot and at right angles to the pull wire and strap. As a result, the pull wire 16 begins to cool, and after a period of time contraction of the pull Wire 16 snaps the vane and the pull wire means to its initial position. The foregoing operations are continued resulting in alternating operation of the vane and signal lamps until such time as a circuit controlling switch is opened.

While the present invention has been described in connection with the details of particular illustrated embodiments thereof, it should be understood that the present invention is not limited to these details, except insofar as set forth in the accompanying claims.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. In apparatus of the type described, a vane of resilient metallic material having a slot extending from one end toward the center of the vane, biasing means at one side of and at said one end of the vane attached at its ends to the varie at substantially right angles to the slot to llex the one end of the vane parallel to the slot and to move the slotted region in one direction away from the biasing means, heat expansible electrically conductive pull means attached at its ends to vane at the other side of the vane and disposed generally parallel to the biasing means near the closed end of the slot, said pull means having a length such that in its unexpanded or contracted condition it is spaced from the vane and liexes the vane in a second and opposite direction toward the biasing means, a base, a mounting bracket on the base secured to the vane between the pull means and opposite end of the vane, a

contact mounted on the pull means and movable therewith, a stationary contact engageable by said movable contact, mounting means on the base for the stationary contact, circuit terminals on the base connected to said mounting bracket and contact mounting means for sup plying current to the pull means to heat the latter when said contacts are in engagement, the biasing means and expansible pull means effecting in response to alternate heating and cooling and accompanying expansion and contraction of the pull means a snap action movement of the vane between two positions in which the vane is alternately flexed in opposite directions with accompanying movement of the pull means in opposite directions to effect alternate disengagement and engagement of the contacts.

2. In apparatus as claimed in clarn 1, in which the biasing means and pull means are each constituted by a metallic strap, and the mounting bracket is secured to the vane in or slightly olf line with respect to the slot.

3. In apparatus as claimed in claim 1, in which the vane has a projection extending toward the biasing means to determine the angular relationship of the vane and biasing means in the contracted position of the pull means.

4. In apparatus as claimed in claim 2, in which the vane has a projection extending toward the biasing means to determine the angular relationship of the vane and biasing means in the contracted position of the pull means.

5. In apparatus of the type described including a resilient vane, means supporting the vane, and means comprising vane biasing means and heat expansible pull wire means attached to the vane at opposite sides of the latter for effecting snap action of the vane between two positions in response to alternate heating and cooling of the pull wire means, wherein the improvement comprises constructing the vane with a slot disposed transversely of the biasing means and extending inwardly from an edge of the vane to near the center of the vane and in which the biasing means is constituted by a strap extending across the slotted portion of the vane and parallel to and laterally spaced relative to the pull Wire means.

6. In apparatus as claimed in claim 5, including means providing a limit angular relationship between the vane and biasing means in the cold position of the pull wire means.

References Cited UNITED STATES PATENTS 2,166,238 7/1939 Davis 337 -391 2,299,767 10/ 1942 Schmidinger 33714O 2,878,340 3/1959 Uhl 337--141 3,174,013 3/1965 Siiberg 337-135 BERNARD A. GILHEANY, Primary Examiner D. M. MORGAN, Assistant Examiner U.S. Cl. X.R. 337-138, 391 

